Estimation of genetic parameters for milk traits in Romanian local sheep breed

ABSTRACT Objective. Estimate the genetic parameters for milk traits in a Romanian local sheep population Teleorman Black Head. Material and methods. Records of 262 sheep belonging to 17 rams and 139 ewes were used in the study. The following traits were investigated: milk yield, fat yield, protein yield, fat percentage and protein percentage. The genetic parameters were estimated using the Restricted Maximum Likelihood method, with a model including maternal effects. Results. The results from our study revealed that direct heritability estimates were moderate for milk yield (0.449), fat yield (0.442), protein yield (0.386) while for protein percentage (0.708) and fat percentage (0.924) were high. The high direct and maternal genetic correlation was between milk yield and protein yield (0.979, 0.973) and between protein yield and fat yield (0.952, 0.913) while the phenotypic correlation between the milk yield and fat yield (0.968), the milk yield and protein yield (0.967), fat yield and protein yield (0.936) was high and positive. Conclusions. The genetic parameters are important in selection program on this breed for genetic improvement

Relationship between gene polymorphism and milk production traits in Teleorman Black Head sheep breed

ABSTRACT Objective. This study is a preliminary step of a larger national program aimed to develop a strategy for “in situ” preservation of Teleorman Black Head sheep population. In this paper we estimated the effect of β-lactoglobulin, casein and prolactin on some quantitative and qualitative milk traits in this local sheep population. Material and methods. Genotyping methodology included PCR for CSN3 (A and B alleles) and PCR-RFLP for LGB (A and B alleles) and PRL (T and C alleles), respectively. Repeated milking and milk composition analysis were used for the polymorphism effect estimation. Results. No association between CSN3 polymorphism and milk traits was found. Effect of LGB on production traits was quite constant. Genotype AA performed better than BB. PRL marker effect showed small differences than LGB. Concerning milk, fat and protein yield, AA genotype for PRL had a smaller positive impact than AA genotype for LGB. Regarding fat and protein content, PRL showed a negative effect for AA and positive for BB genotype, respectively. Conclusions. Positive association between LGB and milk yield and composition recommend this candidate gene like marker for a future MAS program. Although PRL gene is also associated with an increased milk quantity, inverse response over milk composition must be considered in MAS strategy. Our study demonstrated that both LGB and PRL markers could became an advent of MAS utilization in Romanian dairy sheep breeding industry.   RESUMEN Objetivo. Este estudio es un paso preliminar de un programa nacional más amplio destinado a desarrollar una estrategia para la conservación “in situ”de la población de ovejas Cabeza Negra de Teleorman. En este trabajo se estimó el efecto de la β-lactoglobulina, caseína y prolactina en algunos rasgos cuantitativos y cualitativos de la leche en esta población de ovejas locales. Material y métodos. Metodología de PCR para genotipificación incluido CSN3 (A y B alelos) y PCR-RFLP para LGB (A y B alelos) y PRL (T y C alelos). Análisis y composición de la leche de ordeños repetidos se utilizaron para estimación el efecto del polimorfismo. Resultados. No se encontró asociación entre el polimorfismo y la leche rasgos CSN3. Efecto de LGB en los rasgos de producción era bastante constante. Genotipo AA obtenido mejores resultados que BB. Efecto marcador PRL mostró pequeñas diferencias que LGB. En cuanto a la leche grasa y proteína el genotipo AA para PRL tuvo un impacto positivo más pequeño que el genotipo AA para LGB. En cuanto a contenido de grasa y proteína, PRL mostró un efecto negativo para AA y positivo para BB genotipo. Conclusiones.La asociación positiva entre LGB y la producción de leche y la composición recomienda este gen candidato como marcador para un futuro programa de MAS. Aunque gen PRL también se asocia con un incrementoen la cantidad de leche, la respuesta inversa sobre composición de la leche debe ser considerado en la estrategia de MAS. Nuestro estudio demostró que los marcadores tanto LGB y PRL podrían venir a ser utilizados en MAS en la industria rumanade cría deovejas lecheras